LOS ANGELES – Repairs to the earthquake-damaged Washington Monument may force the skyline-defining obelisk to be closed until spring 2014, a spokeswoman for the National Park Service said Monday.

In a telephone interview, spokeswoman Carol Johnson said repairs could take 12 to 18 months. Bidding on the $15 million repair project is expected at the end of July and the contract will be awarded in the fall. On that timeline, the most optimistic reopening would be in the fourth quarter of 2013, but it could be as late as spring 2014.

“We know it is a disappointment,” Johnson said. “We want to get it done as quickly as possible but correctly.”

On Aug. 23, 2011, a magnitude-5.8 earthquake shook the region, causing cracks near the top of the 555-foot monument. It has been closed ever since.

Plans for the project were released Monday for comment.